Domain Controllers

Domain controllers are computers running Windows NT Server that use one shared directory to store security and user-account information for the entire domain; they comprise a single administrative unit. Within a domain, domain controllers manage all aspects of user/domain interactions. Windows NT domain controllers use the information in the directory database to authenticate users logging on to domain accounts. There are two types of domain controllers:

• The primary domain controller (PDC), which tracks changes made to domain accounts and stores the information in the directory database. A domain has one PDC.
• A backup domain controller (BDC), which maintains a copy of the directory database. This is periodically synchronized with the directory database on the PDC. A domain can have multiple BDCs.

For more information about domain controllers, see "Managing Windows NT Server Domains" the Microsoft Windows NT Server 4.0 Concepts and Planning Guide.